Jetting tool for well cleaning

ABSTRACT

The invention provides for a jetting tool for use with a drillstring. The tool generally includes a tubular main body having an inlet and an outlet arranged in fluid communication via a fluid conduit, the main body defining at least one aperture along its length. The tool also includes an elongate outer ring assembly configured for fitment about the main body to enclose the at least one aperture. This ring assembly defines an upper circumferential fluid port and a lower circumferential fluid port, each port configured to operatively direct fluid towards the other. The tool also typically includes a valve assembly receivable inside the fluid conduit, the valve assembly displaceable between a drilling position, wherein fluid is able to pass from the inlet to the outlet via the fluid conduit, and a jetting position, in which fluid is diverted from the inlet to the upper and lower fluid ports via the aperture. The valve assembly is configured to displace to the drilling position upon receiving an activator body via pressurised fluid through the drillstring.

BACKGROUND OF THE INVENTION

This invention relates to a jetting tool for well cleaning.

DESCRIPTION OF THE PRIOR ART

Reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

Jetting tools are known in the art and are generally down-hole devices that jet a high-pressure, typically sand-laden, fluid stream to clean out wellbore holes. For example, U.S. Pat. No. 6,732,793 describes a jetting tool assembly for use in cleaning tubular components used in drilling for gaseous or liquid hydrocarbons in producing formations, said assembly being connectable to a hollow drillstring and having a first mode of operation, which allows through-flow of fluid and lengthwise of the drillstring, and a second mode of operation, which routes the fluid transversely outwardly of the drillstring.

There are a number of shortcomings with known jetting tools, especially their ability to effectively clean boreholes and/or assist in removing coal fines or silt from a void between a borehole and a perforated casing. Such perforated casings are known in the art and are typically used to line a well to allow gas to enter the casing from the producing formations and thereby exit the well.

SUMMARY OF THE PRESENT INVENTION

According to an aspect of the invention there is provided a jetting tool for use with a drillstring, the tool including:

-   -   a body assembly having an inlet for coupling to the drillstring         to allow fluid to be supplied therefrom, the body assembly         defining first and second substantially circumferential fluid         ports, the first and second fluid ports being spaced apart along         the body assembly, and each port being configured to operatively         direct the fluid outwardly from the body assembly and towards         the other port.

Typically the body assembly includes:

-   -   a tubular body including:         -   the inlet; and         -   first and second sets of circumferentially spaced apertures;             and,     -   first and second ring bodies, each ring body being attached to         the tubular body to thereby define the first and second         substantially circumferential fluid ports.

Typically the first and second fluid ports are defined by a gap between shoulders of the tubular body and the first and second ring bodies.

Typically the body assembly includes a third set of circumferentially spaced apertures arranged between the first and second sets of circumferentially spaced apertures.

Typically the body assembly includes:

-   -   a tubular main body having an inlet and an outlet arranged in         fluid communication via a fluid conduit, the main body defining         at least one aperture along its length; and,     -   an elongate outer ring assembly configured for fitment about the         main body to enclose the at least one aperture, the ring         assembly defining an upper circumferential fluid port and a         lower circumferential fluid port, each port configured to         operatively direct fluid towards the other.

Typically the tool includes:

-   -   a valve assembly receivable inside the fluid conduit, the valve         assembly displaceable between a drilling position, wherein fluid         is able to pass from the inlet to the outlet via the fluid         conduit, and a jetting position, in which fluid is diverted from         the inlet to the upper and lower fluid ports via the aperture,         the valve assembly configured to displace to the drilling         position upon receiving an activator body via pressurised fluid         through the drillstring.

Typically, the at least one aperture includes a plurality of slots axially spaced about a portion of the main body.

Typically, the main body includes a flange for positioning the outer ring assembly. Typically, the jetting tool includes a fluid tight seal to prevent fluid leakage between the main body and the outer ring assembly.

Typically, the circumferential fluid ports include slots around a respective upper and lower circumference of the ring assembly, the slots separated a predetermined distance.

Typically, the predetermined distance is in the range of 10 cm to 80 cm.

Typically, the valve assembly includes a hollow elongate stem shaped and dimensioned for coaxial fitment into the fluid conduit, the stem having a receptacle for receiving the activator body.

Typically, the receptacle is positioned towards a lower end of the stem to facilitate in uniform fluid dispersal between the fluid ports when the valve assembly is in the jetting position.

Typically, the jetting tool includes biasing means configured to bias the valve assembly into the drilling position.

Typically, the biasing means includes a spring.

Typically, the jetting tool includes a valve seal to prevent leakage between the valve assembly and the main body.

Typically the circumferential fluid ports are separated by a predetermined distance.

Typically the predetermined distance is in the range of 10 cm to 80 cm.

Typically the circumferential fluid ports are shaped and configured so that fluid is ejected therefrom at an angle relative to the main body.

Typically the angle is in the range of 10° to 85°.

Typically the circumferential fluid ports are arranged to define a jetting zone positioned between the circumferential fluid ports.

According to another aspect of the invention there is provided a jetting tool for use with a drillstring, the tool including:

-   -   a tubular main body having an inlet and an outlet arranged in         fluid communication via a fluid conduit, the main body defining         at least one aperture along its length;     -   an elongate outer ring assembly configured for fitment about the         main body to enclose the at least one aperture, the ring         assembly defining an upper circumferential fluid port and a         lower circumferential fluid port, each port configured to         operatively direct fluid towards the other;     -   a valve assembly receivable inside the fluid conduit, the valve         assembly displaceable between a drilling position, wherein fluid         is able to pass from the inlet to the outlet via the fluid         conduit, and a jetting position, in which fluid is diverted from         the inlet to the upper and lower fluid ports via the aperture,         the valve assembly configured to displace to the drilling         position upon receiving an activator body via pressurised fluid         through the drillstring.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of the present invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 shows an exploded diagrammatic representation of a jetting tool for use with a drillstring;

FIG. 2 shows a side schematic view of a main body of the jetting tool;

FIG. 3 shows a side sectional view of the main body along the line A-A as indicated in FIG. 3A;

FIG. 4 shows a perspective representation of an outer ring assembly of the jetting tool;

FIG. 5 shows a side schematic view of the outer ring assembly;

FIG. 6 shows a side sectional view of the outer ring assembly along the line A-A as indicated in FIG. 6A;

FIG. 7 shows an exploded side representation of the outer ring assembly;

FIG. 8 shows an exploded perspective schematic representation of the outer ring assembly;

FIG. 9 shows a side schematic representation of a ring body of the outer ring assembly;

FIG. 10 shows a perspective representation of the ring body;

FIG. 11 shows a side sectional representation of the ring body along the line A-A as indicated in FIG. 11A;

FIG. 12 shows a perspective representation of a lower sealing ring of the outer ring assembly;

FIG. 13 shows a side schematic representation of the lower sealing ring;

FIG. 14 shows a side sectional representation of the lower sealing ring along the line A-A as indicated in FIG. 14A;

FIG. 15 shows a perspective representation of an upper sealing ring of the outer ring assembly;

FIG. 16 shows a side schematic representation of the upper sealing ring;

FIG. 17 shows a side sectional representation of the upper sealing ring along the line A-A as indicated in FIG. 17A;

FIG. 18 shows a side diagrammatic representation of a valve assembly of the jetting tool;

FIG. 19 shows a side sectional representation of the valve assembly along the line B-B as indicated in FIG. 19A;

FIG. 20 shows an exploded diagrammatic representation of the valve assembly;

FIG. 21 shows a side sectional representation of the jetting tool along the line A-A as indicated in FIG. 21 A with,the valve assembly in a drilling position; and

FIG. 22 shows a side sectional representation of the jetting tool along the line A-A as indicated in FIG. 22A with the valve assembly in a jetting position;

FIG. 23 shows an exploded side representation of a second example of a jetting tool for use with a drillstring;

FIG. 24 shows a side representation of the jetting tool of FIG. 23;

FIG. 25 shows a cross sectional representation along the line A-A as indicated in FIG. 23; and,

FIG. 26 shows a side representation of a jetting zone produced using s jetting tool.

DETAILED DESCRIPTION OF PREFERRED EXAMPLES

With reference now to FIG. 1 of the drawings, there is shown an example of a jetting tool 10 for use with a drillstring (not shown). As is known in the art, a drill string is, used together with some manner of drilling rig as a column, or string, of drill pipe or tube that transmits drilling fluid (typically via compressors and/or mud pumps) and rotational power (generally via a drive mechanism) to a drill bit. The term is loosely applied as an assembled collection of the drill pipe or tube, drill collars, tools and drill bit. The drill string is hollow so that drilling fluid can be pumped down through it and circulated back up a void between the drill string and a drilling formation. It is to be appreciated that the term “fluid” includes any substance, such as a liquid or gas, that is capable of flowing and that changes its shape when acted upon by a force. The ‘term drillstring will therefore be understood to include tubing, or other similar arrangements that can be in drilling or on a drilling rig.

The jetting tool 10 generally forms part of the bottom hole assembly (BHA), where the BHA is made up of tools which may include a drill bit which is used to break-up the rock formations and/or packers or plugs of a well, drill collars which are heavy, thick-walled tubulars used to apply weight to the drill bit, and stabilizers which keep the drilling assembly centered in the hole. The BHA may also contain other components such as a downhole motor, rotary steerable system, measurement while drilling (MWD), and logging while drilling (LWD) tools. In this example, the function of the jetting tool 10 is twofold: firstly the jetting tool 10 allows fluid to pass to the drill bit, and secondly the jetting tool 10 can be used to direct fluid laterally towards the borehole, for example to remove coal fines or silt from the void behind a perforated casing and/or to allow similar cleaning of a hole or well drilled by the bit.

In the current example, the jetting tool 10 includes a tubular main body 12, an outer ring assembly 30, and a valve assembly 50. In use, the tool 10 is generally activated by means of an activator body 70 which is passed down the drillstring via the fluid, as described in more detail below. Each of the above components will now be considered in closer detail.

Referring now to FIGS. 2 and 3 of the drawings, the tubular main body 12 is shown in more detail. The main body 12 includes an inlet 14 and an outlet 16 which are arranged in fluid communication via a fluid conduit 24, as shown. During drilling operations, the drilling fluid enters the tubular main body 12 via the inlet 14 to pass through the conduit 24 and exit the main body 12 at the outlet 16.

The main body 12 generally defines at least one aperture 18 along its length. In the current example, the main body 12 defines a plurality of slots 18 which are axially spaced about a portion of the main body 12, as shown. The slots 18 are spaced about a central portion of the main body, with the conduit 24 arranged in fluid communication with the slots 18 by means of passages 28. As such, if fluid enters the main body 12 via the inlet 14, it can exit via the passages 28 leading to the slots 18, as well as via the outlet 16. However, as described in more detail below, the valve assembly 50 only allows fluid to exit via the outlet 16 or, alternatively, the slots 18, but generally not both at the same time.

The main body 12 also includes a valve seat 26 for receiving and locating a valve head 52 of the valve assembly 50, as described in more detail below. The main body 12 is shaped and configured to receive the outer ring assembly 30. To this end, the main body 12 defines a flange 20 for positioning the outer ring assembly 30. When received, the outer ring assembly 30 generally abuts the flange 20, which keeps the outer ring assembly 30 in place about the main body 12.

An example of the outer ring assembly 30 is shown in more detail in FIGS. 4 to 8. The outer ring assembly 30 generally includes an elongate ring body 31with an upper sealing ring 36 and a lower sealing ring 38 fixed thereto at respective upper and lower ends of the ring body 31. As mentioned above, the outer ring assembly 30 is configured for fitment about the main body 12 in order to enclose the slots 18 in the main body.

In addition, the outer ring assembly 30 defines an upper circumferential fluid port 32 and a lower circumferential fluid port 34. In the current example, these fluid ports 32 and 34 are formed by means of an interaction between the ring body 31 and the respective sealing rings 36 and 38. Whilst the fluid ports 32, 34 are described as being circumferential, it will be appreciated that the fluid ports may not extend continuously around the circumference of the jetting tool, and may be formed from a series of slots or the like, that extend substantially

FIGS. 9 to 11 show the ring body 31 in more detail. The ring body 31 defines upper projections 42 and lower holes 44, as shown. Similarly, the lower sealing ring 38 (shown in more detail in FIGS. 12 to 14) is shaped, dimensioned and configured to complementarily engage the lower end of the ring body 31 so that the holes 44 and the lower sealing ring 38 define spaces 46 via which fluid can pass from inside the ring body 31 to the lower fluid port 34.

Similarly, upper sealing ring 36 (shown in more detail in FIGS. 15 to 17) is shaped, dimensioned and configured to complementarily engage an upper end of the ring body 31 so that the projections 42 and the upper sealing ring 36 define spaces 46 via which fluid can pass from inside the ring body 31 to the upper fluid port 34.

Both the upper and lower sealing rings 36 and 38 include fluid tight seals 48 to prevent fluid leakage between the main body 12 and the outer ring assembly 30 when the outer ring assembly 30 is fitted about the main body 12. As explained above, these seals 48 effectively prevent fluid from passing between the sealing rings 36 and 38 and the main body 12 such that the fluid can only exit via the fluid ports 32 and 34 when the fluid is directed to the outer ring assembly 30.

In the current example, the circumferential fluid ports 32 and 34 are defined by the interaction between the sealing rings 36 and 38 and the ring body 31 as slots extending around the upper and lower circumferences of the ring assembly 30, as shown. These slots of ports 32 and 34 are typically separated a predetermined distance from each other. In different examples, this predetermined distance can be anywhere in the range of, for example, 10cm to 80cm, depending on design requirements. However, it is to be appreciated that this distance range can vary and the current arrangement is not limited thereto.

The fluid ports 32 and 34 are typically arranged and configured to direct fluid passing through them towards each other, i.e. the upper port 32 directs fluid towards the lower port 34 and vice versa. To accomplish this, the ports 32 and 34 are generally shaped and configured so that the fluid is ejected therefrom at an angle relative to the main body 12. Typically, the angle at which fluid is ejected can be in the range of 10° to 85° (generally around 45°) relative to the length of the main body 12, according to requirements.

The arrangement of the fluid ports 32 and 34 is considered a particular advantage of the current arrangement in that prior art arrangements are designed to release the fluid through a series of lateral ports. These prior art arrangements generally direct the fluid directly sideways of the tool and into a casing of the drilling operation which results in a minimal cleaning effect. In contrast, the jetting tool 10 of the current arrangement features the two fluid ports 32 and 34 typically extending about the entire circumference of the tool 10.

In one example, these ports 32 and 34 are positioned a predetermined distance apart and angled towards each other at an angle of 45° in order to create a jetting zone of high pressure fluid in the area between the fluid ports 32, 34 when the valve assembly 50 is in a jetting position. Trial results to date have shown that this arrangement significantly increases a volume of fluid passing through the fluid ports 32 and 34 and significantly reduces an amount of bypass. In addition, a secondary advantage of the configuration of the ports 32 and 34 is that a venturi effect is formed directly above the high pressure zone which aids in facilitating the circulation of loosened silt to the surface. Additionally, by directing fluid towards a common jetting zone, this maximizes the amount of fluid provided to the jetting zone, further enhancing the cleaning effect. The ring body 31 may also defines fluid apertures 40 in a side thereof to facilitate in the removal of silt and dirt loosened by the action of the fluid ports 32 and 34. These fluid apertures 40 can be spaced around the ring body 31 at different positions and are typically configured to direct fluid sideways of the main body 12 to facilitate in removal of loosened silt and/or dirt.

It is to be appreciated that in another example, the fluid ports 32 and 34 do not extend completely around a periphery or circumference of the outer ring assembly 30. For example, each fluid port 32 or 34 can include a number of slots arranged along the same circumference of the ring assembly 30, or the like. Alternatively, a fluid port 32 or 34 may only extend substantially about a circumference of the ring assembly 30.

Referring now to FIGS. 18 to 20 of the drawings, an example of the valve assembly 50 is shown in more detail. The valve assembly 50 is generally receivable inside the fluid conduit 24 of the main body 12, with the valve assembly 50 arranged to be displaceable between a drilling position, wherein fluid is able to pass from the inlet 14 to the outlet 16 via the fluid conduit 24, and a jetting position, in which fluid is diverted from the inlet 14 to the upper and lower fluid ports 32 and 34 via the apertures or slots 18 in the main body 12.

In the current example, the valve assembly 50 includes a hollow elongate valve stem 56 with a valve head 52. The valve assembly also includes a float or flapper valve 72 inserted into the conduit 24 of the main body 12 above the valve assembly 50, as shown. The float 72 is required to prevent pressurized fluid from exiting the drillstring, as is know in the art. The valve head 52 rests inside the valve seat 26 of the main body 12 and abuts in a sealing manner against the float 72, which typically includes a rubber seal at this abutting surface, to seal the valve seat 26 from the conduit 24 when in the drilling position. The valve stem 52 is hollow and effectively forms a second conduit 53 inside the conduit 24 of the main body 12 when in use, allowing fluid to pass through the valve assembly 50.

The valve assembly 50 further includes valve spacers 54 and a valve shoulder 57 to position and space the valve assembly 50 inside the conduit 24 of the main body 12. These spacers 54 and shoulder 57 ensure that there is space for fluid to pass to the passages 28 of the main body 12 between the stem 56 of the valve assembly 50 and the conduit 24 of the main body 12 when the valve assembly 50 is in the jetting position.

The valve assembly 50 is configured to displace into the jetting position upon receiving an activator body 70 under pressure from the fluid passing through the drillstring. This activator body is typically a ball or the like. The valve assembly 50 also includes a receptacle 58 for receiving the activator body. The receptacle 58 is typically positioned towards a lower end of the valve stem 56 to facilitate in uniform fluid dispersal between the fluid ports 32 and 34 of the outer ring assembly 30 when the valve assembly 50 is in the jetting position, as described in more detail below. The receptacle 58 is typically machined as a lower part of the valve stem 56, or the like. However, in further examples, the receptacle 58 may be positioned at any position along the valve assembly 50, depending on requirements.

The valve shoulder 57 also includes valve seals 60 to prevent leakage between the valve assembly 50 and the main body 12. The valve seals 60 are typically kept in place on the shoulder 57 by means of seal retaining rings 62. In effect, the valve seals 60 prevents fluid passing from the second conduit 53 of the valve stem 56 to the outlet 16 of the main body when in the jetting position. However, it is to be appreciated that different examples may include different valve seal configurations.

The jetting tool 10 also generally includes a biasing means 74, such as a spring, configured to bias the valve assembly 50 into the drilling position, i.e. where the valve head 52 engages the float 72 on top of the valve seat 26. The current example also includes a stopper block, 76 to keep the spring 74 in position in the conduit 24 of the main body 12. In addition, the stopper block 76 generally also determines a lower position of the valve assembly 50 which ensures that the valve head 52 is correctly located inside the valve seat 26 and the conduit 24. In another example, the stopper block 76 may be included as a machined part of the main body 12.

Referring now to FIG. 21 of the drawings, an assembled jetting tool 10 is shown with the valve assembly 50 in the drilling position, i.e. the valve head 52 engages with the float 72 on top of the valve seat 26 of the main body 12. In this position, any fluid entering the main body 12 via the inlet 14 is able to pass through the second conduit 53 of the valve stem 56 and exit the tool 10 via the outlet 16, allowing the fluid to be supplied to a drill head, or the like.

FIG. 22 shows the jetting tool 10 with the valve assembly 50 in the jetting position. In this position, the activator body 70 is received in the receptacle 58 of the valve assembly 50, as shown. The activator body or ball 70 blocks the second conduit 53 of the valve assembly 50 and the pressure of the fluid overcomes the biasing means 74 so that the entire valve stem 56 is forced downwards into the main body 12.. This downwards movement of the valve stem 56 causes the valve head 52 to disengage from the float 72 and move down into the valve seat 26 of the main body 12, arranging the fluid conduit 24 of the main body 12 in fluid communication with the fluid space 78 between the valve stem 52 and the conduit 24, as shown. Fluid is now able to bypass the valve head 52, enter the valve seat 26 and flow into the fluid space 78.

Fluid is then able to pass from the inlet 14 to the passages 28 to reach the slots 18 defined by the main body 12. As mentioned above, the slots 18 are in fluid communication with the outer ring assembly 30 where the sealing rings 36 and 38 forces the fluid to escape via the fluid ports 32 and 34, as indicated by fluid flow arrows 80. In another example, different passages may direct fluid to different areas of the outer ring assembly 30. For example, some of the passages 28 in the main body 12 may be configured to lead directly to spaces 46, or the like, depending on requirements.

It is regarded as advantageous that the jetting tool 10 of the current arrangement provides for improved cleaning of perforated casings and/or wellbores without requiring removal of a bottom hole assembly (BHA) from the well.

In one example, the above described system can be used to clean the borehole once drilling of the borehole is complete. For example, once the drilling process is completed, the activator body 70 can be inserted into the fluid provided to the BHA, thereby switching the jetting tool to jetting mode. As the drillstring and hence the BHA is removed from the borehole, this raises the jetting tool, allowing the borehole to be cleaned along the bore hole length.

In any alternative example however, the jetting tool can be designed to operate in a single jetting mode only. An example of a jetting tool for operating in this configuration is described in FIGS. 23 to 26.

In this example, the jetting tool includes 110 includes a body 112 having an inlet 114 in fluid communication with a fluid conduit 124. An outlet 116 may be provided an opposite end of the fluid conduit 124, and alternatively the fluid conduit 124 may be closed at the end opposite the inlet 114. The -fluid conduit 124 includes two sets of circumferentially spaced apertures 128.1, 128.2 spaced apart along the length of the body 112. A third set of apertures 140 may be provided between the first and second sets of apertures 128.1, 128.2.

First and second sealing rings 136.1, 136.2 are attached to the body 112, so as to define circumferential fluid ports 132.1, 132.2. Each sealing ring 136.1, 136.2 includes a respective seal 148.1, 148.2 for sealingly engaging a corresponding seat 182.1, 182.2, provided on the body 112. A gap 184.1, 184.2 provided between shoulders 180.1, 180.2, 182.1, 182.2, provided on the body 112 and sealing rings 136.1, 136.2 defines the first and second fluid ports 132.1, 132.2.

In this example, the shoulders 180.1, 180.2, 182.1, 182.2 are arranged so that fluid is ejected from each fluid port 132.1, 132.2, towards the other fluid port 132.1, 132.2, at an angle relative to the body 112, as shown for example by the arrows 190.1, 190.2, thereby defining a jetting zone 195 between the fluid ports 132.1, 132.2. The angle is typically in the range of 10° to 85° (generally around 45°), although any angle may be used to define an appropriate jetting zone. It will be appreciated that in general it is preferred that fluid from each of the fluid ports impacts on the borehole surface at substantially the same location, thereby maximizing the cleaning effect of the jetting tool. Accordingly, the angle selected will depend on factors such as the diameter of the borehole 200, the diameter of the jetting tool, and the separation between the fluid ports 132.1, 132.2.

In addition to the first and second fluid ports 132.1, 132.2, the body may include a third set of circumferentially spaced apertures 140, which are positioned between the first and second set of apertures, to thereby define a third fluid port. The third fluid port directs additional fluid into the jetting zone, thereby further enhancing the cleaning effect provided by the jetting tool.

Accordingly, the above described apparatus describes a jetting tool including a body assembly having an inlet for coupling to the drillstring to allow fluid to be supplied therefrom. The body assembly defines first and second substantially circumferential fluid ports, the first and second fluid ports being spaced apart along the body assembly, and each port being configured to operatively direct the fluid outwardly from the body assembly and towards the other port. This allows the jetting tool to direct fluid supplied via the drillstring into a jetting zone, thereby efficiently cleaning both the surface of the borehole and the region between the borehole and the jetting tool.

In one example, the jetting tool is attached to an end of the drillstring, so that the drillstring and jetting tool combination is used for cleaning only. In another example however, the jetting tool can be coupled to a BHA, such as a drill head, to thereby allow drilling to be performed. The jetting tool can include a valve assembly, which is initially configured to allow fluid to be transferred through the jetting tool to the drill head, during drilling. Once drilling is complete, an activator is inserted into the drillstring, with the activator cooperating with the valve assembly, allowing the jetting tool to be switched to a jetting mode, which in turn allows the borehole to be cleaned, particularly as the drillstring is removed from the borehole.

Many modifications or variations will be apparent to those skilled in the art without departing from the scope of the present invention. All such variations and modifications should be considered to fall within the spirit and scope of the invention broadly appearing and described in more detail herein.

It is to be appreciated that reference to “one example” or “an example” of the invention is not made in an exclusive sense. Accordingly, one example may exemplify certain aspects of the invention, whilst other aspects are exemplified in a different example. These examples are intended to assist the skilled person in performing the invention and are not intended to limit the overall scope of the invention in any way unless the context clearly indicates otherwise.

Features that are common to the art are not explained in any detail as they are deemed to be easily understood by the skilled person. Similarly, throughout this specification, the term “comprising” and its grammatical equivalents shall be taken to have an inclusive meaning, unless the context of use clearly indicates otherwise. 

1. A jetting tool for use with a drillstring, the tool including: a body assembly having an inlet for coupling to the drillstring to allow fluid to be supplied therefrom, the body assembly defining first and second substantially circumferential fluid ports, the first and second fluid ports being spaced apart along the body assembly, and each port being configured to operatively direct the fluid outwardly from the body assembly and towards the other port.
 2. A jetting tool according to claim 1, wherein the body assembly includes: a tubular body including: the inlet; and first and second sets of circumferentially spaced apertures; and, first and second ring bodies, each ring body being attached to the tubular body to thereby define the first and second substantially circumferential fluid ports.
 3. A jetting tool according to claim 2, wherein the first and second fluid ports are defined by a gap between shoulders of the tubular body and the first and second ring bodies.
 4. A jetting tool according to claim 1, wherein the body assembly includes a third set of circumferentially spaced apertures arranged between the first and second sets of circumferentially spaced apertures.
 5. A jetting tool according to claim 1, wherein the body assembly includes: a tubular main body having an inlet and an outlet arranged in fluid communication via a fluid conduit, the main body defining at least one aperture along its length; and, an elongate outer ring assembly configured for fitment about the main body to enclose the at least one aperture, the ring assembly defining an upper circumferential fluid port and a lower circumferential fluid port, each port configured to operatively direct fluid towards the other.
 6. A jetting tool according to claim 5, wherein the tool includes: a valve assembly receivable inside the fluid conduit, the valve assembly being displaceable between a drilling position, wherein fluid is able to pass from the inlet to the outlet via the fluid conduit, and a jetting position, in which fluid is diverted from the inlet to the upper and lower fluid ports via the aperture, the valve assembly configured to displace to the drilling position upon receiving an activator body via pressurised fluid through the drillstring.
 7. The jetting tool of claim 5 6 or claim 7, wherein the at least one aperture includes a plurality of slots circumferentially spaced about a portion of the main body.
 8. The jetting tool of claim 5, wherein the main body includes a flange for positioning the outer ring assembly.
 9. The jetting tool of claim 5, which includes a fluid tight seal to prevent fluid leakage between the main body and the outer ring assembly.
 10. The jetting tool of claim 5, wherein the circumferential fluid ports include slots around a respective upper and lower circumference of the ring assembly, the slots being separated by a predetermined distance.
 11. The jetting tool of claim 10, wherein the predetermined distance is in the range of 10cm to 80cm.
 12. The jetting tool of claim 6, wherein the valve assembly includes a hollow elongate stem shaped and dimensioned for coaxial fitment into the fluid conduit, the stem having a receptacle for receiving the activator body.
 13. The jetting tool of claim 12, wherein the receptacle is positioned towards a lower end of the stem to facilitate in uniform fluid dispersal between the fluid ports when the valve assembly is in the jetting position.
 14. The jetting tool of claim 6, which includes biasing means configured to bias the valve assembly into the drilling position.
 15. The jetting tool of claim 14, wherein the biasing means includes a spring.
 16. The jetting tool of claim 6, which includes a valve seal to prevent leakage between the valve assembly and the main body. 17-25. (canceled)
 26. The jetting tool of claim 1, wherein the circumferential fluid ports are separated by a predetermined distance.
 27. The jetting tool of claim 26, wherein the predetermined distance is in the range of 10 cm to 80 cm.
 28. The jetting tool of claim 1, wherein the circumferential fluid ports are shaped and configured so that fluid is ejected therefrom at an angle relative to the main body.
 29. The jetting tool of claim 28, wherein the angle is in the range of 10° to 85°.
 30. A jetting tool according to claim 1, wherein the circumferential fluid ports are arranged to define a jetting zone positioned between the circumferential fluid ports.
 31. A jetting tool for use with a drillstring, the tool including: a tubular main body having an inlet and an outlet arranged in fluid communication via a fluid conduit, the main body defining at least one aperture along its length; an elongate outer ring assembly configured for fitment about the main body to enclose the at least one aperture, the ring assembly defining an upper circumferential fluid port and a lower circumferential fluid port, each port configured to operatively direct fluid towards the other; a valve assembly receivable inside the fluid conduit, the valve assembly displaceable between a drilling position, wherein fluid is able to pass from the inlet to the outlet via the fluid conduit, and a jetting position, in which fluid is diverted from the inlet to the upper and lower fluid ports via the aperture, the valve assembly configured to displace to the drilling position upon receiving an activator body via pressurised fluid through the drillstring. 